Osteoporosis has become one of the most prevalent bone diseases in developed countries. As the world’s population ages, this complex skeletal disorder is predicted to become an even more widespread and serious health...Osteoporosis has become one of the most prevalent bone diseases in developed countries. As the world’s population ages, this complex skeletal disorder is predicted to become an even more widespread and serious health condition, posing greater societal economic burden. Current therapeutic agents are limited by clinically significant side effects. In this report, we present a case that suggests intra-articular platelet-rich plasma (PRP) injectate may improve bone mineral density (BMD). This observation raises a question with exciting implications—can PRP serve as a viable and relatively safe, targeted treatment option to improve bone density?展开更多
The mid-subtropical forest is one of the biggest sections of subtropical forest in China and plays a vital role in mitigating climate change by sequestering carbon.Studies have examined carbon storage density(CSD) dis...The mid-subtropical forest is one of the biggest sections of subtropical forest in China and plays a vital role in mitigating climate change by sequestering carbon.Studies have examined carbon storage density(CSD) distribution in temperate forests. However, our knowledge of CSD in subtropical forests is limited. In this study, Jiangle County was selected as a study case to explore geographic variation in CSD. A spatial heterogeneity analysis by semivariogram revealed that CSD varied at less than the mesoscale(approximately 2000–3000 m). CSD distribution mapped using Kriging regression revealed an increasing trend in CSD from west to east of the study area.Global spatial autocorrelation analysis indicated that CSD was clustered at the village level(at 5% significance).Some areas with local spatial autocorrelation were detected by Anselin Local Moran's I and Getis-Ord G*. A geographically weighted regression model showed different impacts on the different areas for each determinant. Generally, diameter at breast height, tree height, and stand density had positive correlation with CSD in Jiangle County, but varied substantially in magnitude by location.In contrast, coefficients of elevation and slope ranged from negative to positive. Based on these results, we propose certain measures to increase forest carbon storage,including increasing forested area, improving the quality of the current forests, and promoting reasonable forest management decisions and harvesting strategies. The established CSD model emphasizes the important role of midsubtropical forest in carbon sequestration and provides useful information for quantifying mid-subtropical forest carbon storage.展开更多
Functional morphological alterations of human blood platelets induced by oxidatively modified low density lipoprotein (LDL) were studied with an in vitro model by means of electron microscopy, reflection contrast micr...Functional morphological alterations of human blood platelets induced by oxidatively modified low density lipoprotein (LDL) were studied with an in vitro model by means of electron microscopy, reflection contrast microscopy and quantitative image analysis. The oxidized LDL (50-300 μg/ml) induced the disc-sphere transformation of platelets, the formation of pseudopodia, centralization of granules and degranulation. Platelet plasma membrane was damaged by oxidized LDL leading to a lower electron density of he cytoplasm compared to controls. In an incubation chamber, oxidized LDL-treated platelets sedimented onto the展开更多
The grain density,Nv,in the solid state after solidification of AZ91/SiC composite is a function of maximum undercooling,ΔT,of a liquid alloy.This type of function depends on the characteristics of heterogeneous nucl...The grain density,Nv,in the solid state after solidification of AZ91/SiC composite is a function of maximum undercooling,ΔT,of a liquid alloy.This type of function depends on the characteristics of heterogeneous nucleation sites and number of SiC present in the alloy.The aim of this paper was selection of parameters for the model describing the relationship between the grain density of primary phase and undercooling.This model in connection with model of crystallisation,which is based on chemical elements diffusion and grain interface kinetics,can be used to predict casting quality and its microstructure.Nucleation models have parameters,which exact values are usually not known and sometimes even their physical meaning is under discussion.Those parameters can be obtained after mathematical analysis of the experimental data.The composites with 0,1,2,3 and 4wt.% of SiC particles were prepared.The AZ91 alloy was a matrix of the composite reinforcement SiC particles.This composite was cast to prepare four different thickness plates.They were taken from the region near to the thermocouple,to analyze the undercooling for different composites and thickness plates and its influence on the grain size.The microstructure and thermal analysis gave set of values that connect mass fraction of SiC particles,and undercooling with grain size.These values were used to approximate nucleation model adjustment parameters.Obtained model can be very useful in modelling composites microstructure.展开更多
Ecotones have received great attention due to its critical function in energy flux, species harbor, global carbon sequestration, and land-atmosphere interaction. This study investigated land use pattern and spatial he...Ecotones have received great attention due to its critical function in energy flux, species harbor, global carbon sequestration, and land-atmosphere interaction. This study investigated land use pattern and spatial heterogeneity of the ecotones among agricultural land, forest land, and grassland of the southeastern Da Hinggan Mountains in the northeastern China. The change of these delineated ecotones under different slopes and aridity conditions was analyzed by two landscape indices, edge density(ED) and core area percentage of landscape(CPL), to explore the inter-linkage between spatial structure of ecotones and socioeconomic development and land management. Specifically, the ecotones such as agriculture-forest(AF) ecotone, forest-grassland(FG) ecotone, and agriculture-forestgrassland(AFG) ecotone moved from the arid southeast to the humid northwest. The flat area with small slope is more edge-fragmented than the steep area since the ED decreases as the slope increases. The AF ecotone mostly found in the humid region is moving to more humid areas while the agriculture-grassland(AG) ecotone mostly found in the dry region is moving towards the drier region.展开更多
The side-chain alkylation of toluene with methanol over alkali-cation-containing zeolite Y is an important reaction for industrial production of styrene,but the exact mechanism of this reaction is still unclear.The mo...The side-chain alkylation of toluene with methanol over alkali-cation-containing zeolite Y is an important reaction for industrial production of styrene,but the exact mechanism of this reaction is still unclear.The most accepted opinion is that the Lewis acid-base sites in zeolite Y activate the transformation from methanol to formaldehyde,the side-chain alkylation of toluene with formaldehyde,and the formation of 2-phenylethanol and styrene afterwards.In this study,we investigate the roles of various types of hydroxyl groups that could possibly exist in zeolite Na-Y during this reaction,including the Br6nsted acid sites and the terminal Al-OH and Si-OH groups,respectively.Through density functional theory （DFT） calculations,we find that the Brtnsted acid sites in Na-Y may catalyze the ring alkylation of toluene and be responsible for the formation of xylene,a side product discovered in experiments.More importantly,we find,for the first time,a new reaction pathway from 2-phenylethanol to styrene over various types of hydroxyl groups in Na-Y,which is kinetically more favorable than the conventional pathway.According to our calculation results,the most possible mechanism for this styrene production process may involve reactions over both the Lewis acid-base sites and the hydroxyl groups in Na-Y.展开更多
Sea salt particles containing NaCl are among the most abundant particulate masses in coastal atmosphere. Reactions involving sea salt particles potentially generate Cl radicals, which are released into coastal atmosph...Sea salt particles containing NaCl are among the most abundant particulate masses in coastal atmosphere. Reactions involving sea salt particles potentially generate Cl radicals, which are released into coastal atmosphere. Cl radicals play an important role in the nitrogen and O3 cycles, sulfitr chemistry and particle formation in the troposphere of the polluted coastal regions. This paper aimed at .the heterogeneous reaction between gaseous HNO3 .and solid NaCl. The mech.anis.m was in.vestigatedby density functional theory （DFT）. The results imply that water molecules induce the surface reconstruction, which is essential for the heterogeneous reaction. The surface reconstruction on the defective （710） surface has a barrier of 10.24 kcal.mol-1 and is endothermic by 9.69 kcal.mol-1, whereas the reconstruction on the clean （100） surface has a barrier of 18.46 kcal.mol-1 and isendothermic by 12.96 kcal.mol-1. The surface reconstruction involved in water-adsorbed （710） surface is more energetically favorable. In comparison, water molecules adsorbed on NaCl （100） surface likely undergo water diffusion or desorption. Further, it reveals that the coordination number of the Cl-out is reduced after the surface reconstruction, which assists Clout to accept the proton from HNO3. HCl is released from heterogeneous reactions between gaseous HNO3 and solid NaCl and can react with OH free radicals to produce atomic Cl radicals. The results will offer further insights into the impact of gaseous HNO3 on the air quality of the coastal areas.展开更多
This study is an attempt to establish a suitable speed–density functional relationship for heterogeneous traffic on urban arterials. The model must reproduce the traffic behaviour on traffic stream and satisfy all st...This study is an attempt to establish a suitable speed–density functional relationship for heterogeneous traffic on urban arterials. The model must reproduce the traffic behaviour on traffic stream and satisfy all static and dynamic properties of speed–flow–density relationships. As a first attempt for Indian traffic condition, two behavioural parameters, namely the kinematic wave speed at jam(Cj) and a proposed saturation flow(k), are estimated using empirical observations. The parameter Cjis estimated by developing a relationship between driver reaction time and vehicle position in the queue at the signalised intersection. Functional parameters are estimated using Levenberg–Marquardt algorithm implemented in the R statistical software.Numerical measures such as root mean squared error, average relative error and cumulative residual plots are used for assessing models fitness. We set out several static and dynamic properties of the flow–speed–density relationships to evaluate the models, and these properties equally hold good for both homogenous and heterogeneous traffic states.From the numerical analysis, it is found that very few models replicate empirical speed–density data traffic behaviour.However, none of the existing functional forms satisfy all the properties. To overcome the shortcomings, we proposed two new speed–density functional forms. The uniqueness of these models is that they satisfy both numerical accuracy and the properties of fundamental diagram. These new forms would certainly improve the modelling accuracy, especially in dynamic traffic studies when coupling with dynamic speed equations.展开更多
文摘Osteoporosis has become one of the most prevalent bone diseases in developed countries. As the world’s population ages, this complex skeletal disorder is predicted to become an even more widespread and serious health condition, posing greater societal economic burden. Current therapeutic agents are limited by clinically significant side effects. In this report, we present a case that suggests intra-articular platelet-rich plasma (PRP) injectate may improve bone mineral density (BMD). This observation raises a question with exciting implications—can PRP serve as a viable and relatively safe, targeted treatment option to improve bone density?
基金supported by Science and Technology Major Project of the Hall of Science and Technology of Fujian (No. 2012NZ0001)the Project of National Natural Science Fund of China (No.30671664)
文摘The mid-subtropical forest is one of the biggest sections of subtropical forest in China and plays a vital role in mitigating climate change by sequestering carbon.Studies have examined carbon storage density(CSD) distribution in temperate forests. However, our knowledge of CSD in subtropical forests is limited. In this study, Jiangle County was selected as a study case to explore geographic variation in CSD. A spatial heterogeneity analysis by semivariogram revealed that CSD varied at less than the mesoscale(approximately 2000–3000 m). CSD distribution mapped using Kriging regression revealed an increasing trend in CSD from west to east of the study area.Global spatial autocorrelation analysis indicated that CSD was clustered at the village level(at 5% significance).Some areas with local spatial autocorrelation were detected by Anselin Local Moran's I and Getis-Ord G*. A geographically weighted regression model showed different impacts on the different areas for each determinant. Generally, diameter at breast height, tree height, and stand density had positive correlation with CSD in Jiangle County, but varied substantially in magnitude by location.In contrast, coefficients of elevation and slope ranged from negative to positive. Based on these results, we propose certain measures to increase forest carbon storage,including increasing forested area, improving the quality of the current forests, and promoting reasonable forest management decisions and harvesting strategies. The established CSD model emphasizes the important role of midsubtropical forest in carbon sequestration and provides useful information for quantifying mid-subtropical forest carbon storage.
文摘Functional morphological alterations of human blood platelets induced by oxidatively modified low density lipoprotein (LDL) were studied with an in vitro model by means of electron microscopy, reflection contrast microscopy and quantitative image analysis. The oxidized LDL (50-300 μg/ml) induced the disc-sphere transformation of platelets, the formation of pseudopodia, centralization of granules and degranulation. Platelet plasma membrane was damaged by oxidized LDL leading to a lower electron density of he cytoplasm compared to controls. In an incubation chamber, oxidized LDL-treated platelets sedimented onto the
基金supported financially by the European Community under Marie Curie Transfer of Knowledge grant No. MTKD-CT-2006-042468 (AGH No.27.27.170.304)Polish Ministry of Science and Higher Education for financial support under grant No. N507-44-66-34 (AGH No.18.18.170.325)
文摘The grain density,Nv,in the solid state after solidification of AZ91/SiC composite is a function of maximum undercooling,ΔT,of a liquid alloy.This type of function depends on the characteristics of heterogeneous nucleation sites and number of SiC present in the alloy.The aim of this paper was selection of parameters for the model describing the relationship between the grain density of primary phase and undercooling.This model in connection with model of crystallisation,which is based on chemical elements diffusion and grain interface kinetics,can be used to predict casting quality and its microstructure.Nucleation models have parameters,which exact values are usually not known and sometimes even their physical meaning is under discussion.Those parameters can be obtained after mathematical analysis of the experimental data.The composites with 0,1,2,3 and 4wt.% of SiC particles were prepared.The AZ91 alloy was a matrix of the composite reinforcement SiC particles.This composite was cast to prepare four different thickness plates.They were taken from the region near to the thermocouple,to analyze the undercooling for different composites and thickness plates and its influence on the grain size.The microstructure and thermal analysis gave set of values that connect mass fraction of SiC particles,and undercooling with grain size.These values were used to approximate nucleation model adjustment parameters.Obtained model can be very useful in modelling composites microstructure.
基金Under the auspices of'Strategic Priority Research Program-Climate Change:Carbon Budget and Relevant Issues'of Chinese Academy of Sciences(No.XDA05090310)
文摘Ecotones have received great attention due to its critical function in energy flux, species harbor, global carbon sequestration, and land-atmosphere interaction. This study investigated land use pattern and spatial heterogeneity of the ecotones among agricultural land, forest land, and grassland of the southeastern Da Hinggan Mountains in the northeastern China. The change of these delineated ecotones under different slopes and aridity conditions was analyzed by two landscape indices, edge density(ED) and core area percentage of landscape(CPL), to explore the inter-linkage between spatial structure of ecotones and socioeconomic development and land management. Specifically, the ecotones such as agriculture-forest(AF) ecotone, forest-grassland(FG) ecotone, and agriculture-forestgrassland(AFG) ecotone moved from the arid southeast to the humid northwest. The flat area with small slope is more edge-fragmented than the steep area since the ED decreases as the slope increases. The AF ecotone mostly found in the humid region is moving to more humid areas while the agriculture-grassland(AG) ecotone mostly found in the dry region is moving towards the drier region.
文摘The side-chain alkylation of toluene with methanol over alkali-cation-containing zeolite Y is an important reaction for industrial production of styrene,but the exact mechanism of this reaction is still unclear.The most accepted opinion is that the Lewis acid-base sites in zeolite Y activate the transformation from methanol to formaldehyde,the side-chain alkylation of toluene with formaldehyde,and the formation of 2-phenylethanol and styrene afterwards.In this study,we investigate the roles of various types of hydroxyl groups that could possibly exist in zeolite Na-Y during this reaction,including the Br6nsted acid sites and the terminal Al-OH and Si-OH groups,respectively.Through density functional theory （DFT） calculations,we find that the Brtnsted acid sites in Na-Y may catalyze the ring alkylation of toluene and be responsible for the formation of xylene,a side product discovered in experiments.More importantly,we find,for the first time,a new reaction pathway from 2-phenylethanol to styrene over various types of hydroxyl groups in Na-Y,which is kinetically more favorable than the conventional pathway.According to our calculation results,the most possible mechanism for this styrene production process may involve reactions over both the Lewis acid-base sites and the hydroxyl groups in Na-Y.
基金This work was supported by the National High Technology Research ＆ Development Program of China （No. 2012AA06A301） and the National Natural Science Foundation of China （Grant Nos. 21337001 and 21177076）.
文摘Sea salt particles containing NaCl are among the most abundant particulate masses in coastal atmosphere. Reactions involving sea salt particles potentially generate Cl radicals, which are released into coastal atmosphere. Cl radicals play an important role in the nitrogen and O3 cycles, sulfitr chemistry and particle formation in the troposphere of the polluted coastal regions. This paper aimed at .the heterogeneous reaction between gaseous HNO3 .and solid NaCl. The mech.anis.m was in.vestigatedby density functional theory （DFT）. The results imply that water molecules induce the surface reconstruction, which is essential for the heterogeneous reaction. The surface reconstruction on the defective （710） surface has a barrier of 10.24 kcal.mol-1 and is endothermic by 9.69 kcal.mol-1, whereas the reconstruction on the clean （100） surface has a barrier of 18.46 kcal.mol-1 and isendothermic by 12.96 kcal.mol-1. The surface reconstruction involved in water-adsorbed （710） surface is more energetically favorable. In comparison, water molecules adsorbed on NaCl （100） surface likely undergo water diffusion or desorption. Further, it reveals that the coordination number of the Cl-out is reduced after the surface reconstruction, which assists Clout to accept the proton from HNO3. HCl is released from heterogeneous reactions between gaseous HNO3 and solid NaCl and can react with OH free radicals to produce atomic Cl radicals. The results will offer further insights into the impact of gaseous HNO3 on the air quality of the coastal areas.
文摘This study is an attempt to establish a suitable speed–density functional relationship for heterogeneous traffic on urban arterials. The model must reproduce the traffic behaviour on traffic stream and satisfy all static and dynamic properties of speed–flow–density relationships. As a first attempt for Indian traffic condition, two behavioural parameters, namely the kinematic wave speed at jam(Cj) and a proposed saturation flow(k), are estimated using empirical observations. The parameter Cjis estimated by developing a relationship between driver reaction time and vehicle position in the queue at the signalised intersection. Functional parameters are estimated using Levenberg–Marquardt algorithm implemented in the R statistical software.Numerical measures such as root mean squared error, average relative error and cumulative residual plots are used for assessing models fitness. We set out several static and dynamic properties of the flow–speed–density relationships to evaluate the models, and these properties equally hold good for both homogenous and heterogeneous traffic states.From the numerical analysis, it is found that very few models replicate empirical speed–density data traffic behaviour.However, none of the existing functional forms satisfy all the properties. To overcome the shortcomings, we proposed two new speed–density functional forms. The uniqueness of these models is that they satisfy both numerical accuracy and the properties of fundamental diagram. These new forms would certainly improve the modelling accuracy, especially in dynamic traffic studies when coupling with dynamic speed equations.
